46 tons of water for every million tons would be huge for lunar colonization. Most regolith does not have that concentration it is only the volatile pebbles. The researchers estimated that there was originally about 750 ppm of water in the magma at the time of eruption. It suggests the intriguing possibility that the Moon's interior might have had as much water as the Earth's upper mantle. But even more intriguing: If the Moon's volcanoes released 95% of their water, where did all that water go? Since the Moon's gravity is too feeble to retain an atmosphere, the researchers speculate that some of the water vapor from the eruptions was probably forced into space but some may have gone to the lunar poles. Unless it is very deep, lunar groundwater is unlikely to exist since the Sun heats most of the Moon's surface to over 200°F (100°C).

The findings point to the existence of water deep beneath the moon's surface, transforming scientific understanding of our nearest neighbor's formation and, perhaps, our own. There may also be a more immediately practical application.

"Is there water there? That's important for lunar missions. People could get the water. They could use the hydrogen for energy," said Saal.

Critically, telltale hydrogen molecules were concentrated at the center of samples rather than their surfaces, assuring Saal's team that water was present in an infant moon rather than added by recent bombardment.

If that water in fact came from the Earth, then planetary geologists can be certain that our planet contained water 4.5 billion years ago. That would change the dynamics of models of Earth's formations

In planetary science, volatiles, commonly called ices in the extraterrestrial context, are that group of compounds with low boiling points (see volatile) that are associated with a planet's or moon's crust and/or atmosphere. Examples include nitrogen, water, carbon dioxide, ammonia, hydrogen and methane, all compounds of C, H, O and/or N, as well as sulphur dioxide. In astrogeology, these compounds, in their solid state, often comprise large proportions of the crusts of moons and dwarf planets. In terrestrial geology, the term more specifically refers to components of magma (mostly water vapor and carbon dioxide) that affect the appearance and strength of volcanoes. Volatiles affect the viscosity of the magma, and the tendency to explosive eruptions.